Herbalife activists are calling on investors Carl Ichan (right) and George Soros (left) to sell their stakes in the company.Reuters

Anti-Herbalife activists are turning up the heat on the controversial diet-shake company by knocking on the doors of its billionaire investors — Carl Icahn and George Soros.

One of the company’s fiercest critics, the League of United Latin American Citizens, is urging the boldface financiers to sell their stakes in Herbalife, which it accuses of taking advantage of its largely Hispanic sales force.

The group has fired off letters to Icahn and Soros asking to meet with them on Thursday, the same day Herbalife is set to report earnings.

“Ask yourself if the economic gain you have invested in Herbalife is worth the inhumane treatment and exploitation of our most vulnerable, the undocumented immigrant,” LULAC’s Julie Contreras and Emma Lozano wrote in the letter to Icahn that The Post has reviewed.

They are asking both men “to remove themselves from any financial association with Herbalife,” Contreras said.

The move marks a shift in LULAC’s months-long campaign against the Los Angeles company. The group has focused on applying political pressure and hasn’t really waded into the Wall Street battle over its stock.

Icahn is the biggest Herbalife shareholder, with 19 percent of the stock and five employees on its board of directors.

LULAC is also planning an 11 a.m. prayer vigil in front of Icahn’s Fifth Avenue office in midtown Manhattan that day.

“We believe that you are a moral man and ask for a few minutes of your time so that the victims can share the truth about Herbalife with you,” reads the letter to Icahn. “The people are suffering from a fraudulent company that you support.”

A similar letter was sent to Soros. After stopping at Icahn’s office, the group plans to walk across midtown to the Seventh Avenue offices of Soros Fund Management, and his charity, The Open Society Foundation, which is next door.